/*
 * Copyright (c) 2008, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 *
 *
 *
 *
 *
 *
 *
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 *
 *
 *
 *
 */

package java.lang.invoke;

import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.function.Function;

import sun.invoke.empty.Empty;
import sun.invoke.util.ValueConversions;
import sun.invoke.util.VerifyType;
import sun.invoke.util.Wrapper;
import sun.reflect.CallerSensitive;
import sun.reflect.Reflection;

import static java.lang.invoke.LambdaForm.*;
import static java.lang.invoke.MethodHandleStatics.*;
import static java.lang.invoke.MethodHandles.Lookup.IMPL_LOOKUP;

/**
 * Trusted implementation code for MethodHandle.
 *
 * @author jrose
 */
/*non-public*/ abstract class MethodHandleImpl {

  // Do not adjust this except for special platforms:
  private static final int MAX_ARITY;

  static {
    final Object[] values = {255};
    AccessController.doPrivileged(new PrivilegedAction<Void>() {
      @Override
      public Void run() {
        values[0] = Integer.getInteger(MethodHandleImpl.class.getName() + ".MAX_ARITY", 255);
        return null;
      }
    });
    MAX_ARITY = (Integer) values[0];
  }

  /// Factory methods to create method handles:

  static void initStatics() {
    // Trigger selected static initializations.
    MemberName.Factory.INSTANCE.getClass();
  }

  static MethodHandle makeArrayElementAccessor(Class<?> arrayClass, boolean isSetter) {
    if (arrayClass == Object[].class) {
      return (isSetter ? ArrayAccessor.OBJECT_ARRAY_SETTER : ArrayAccessor.OBJECT_ARRAY_GETTER);
    }
    if (!arrayClass.isArray()) {
      throw newIllegalArgumentException("not an array: " + arrayClass);
    }
    MethodHandle[] cache = ArrayAccessor.TYPED_ACCESSORS.get(arrayClass);
    int cacheIndex = (isSetter ? ArrayAccessor.SETTER_INDEX : ArrayAccessor.GETTER_INDEX);
    MethodHandle mh = cache[cacheIndex];
    if (mh != null) {
      return mh;
    }
    mh = ArrayAccessor.getAccessor(arrayClass, isSetter);
    MethodType correctType = ArrayAccessor.correctType(arrayClass, isSetter);
    if (mh.type() != correctType) {
      assert (mh.type().parameterType(0) == Object[].class);
      assert ((isSetter ? mh.type().parameterType(2) : mh.type().returnType()) == Object.class);
      assert (isSetter || correctType.parameterType(0).getComponentType() == correctType
          .returnType());
      // safe to view non-strictly, because element type follows from array type
      mh = mh.viewAsType(correctType, false);
    }
    mh = makeIntrinsic(mh, (isSetter ? Intrinsic.ARRAY_STORE : Intrinsic.ARRAY_LOAD));
    // Atomically update accessor cache.
    synchronized (cache) {
      if (cache[cacheIndex] == null) {
        cache[cacheIndex] = mh;
      } else {
        // Throw away newly constructed accessor and use cached version.
        mh = cache[cacheIndex];
      }
    }
    return mh;
  }

  static final class ArrayAccessor {

    /// Support for array element access
    static final int GETTER_INDEX = 0, SETTER_INDEX = 1, INDEX_LIMIT = 2;
    static final ClassValue<MethodHandle[]> TYPED_ACCESSORS
        = new ClassValue<MethodHandle[]>() {
      @Override
      protected MethodHandle[] computeValue(Class<?> type) {
        return new MethodHandle[INDEX_LIMIT];
      }
    };
    static final MethodHandle OBJECT_ARRAY_GETTER, OBJECT_ARRAY_SETTER;

    static {
      MethodHandle[] cache = TYPED_ACCESSORS.get(Object[].class);
      cache[GETTER_INDEX] = OBJECT_ARRAY_GETTER = makeIntrinsic(getAccessor(Object[].class, false),
          Intrinsic.ARRAY_LOAD);
      cache[SETTER_INDEX] = OBJECT_ARRAY_SETTER = makeIntrinsic(getAccessor(Object[].class, true),
          Intrinsic.ARRAY_STORE);

      assert (InvokerBytecodeGenerator
          .isStaticallyInvocable(ArrayAccessor.OBJECT_ARRAY_GETTER.internalMemberName()));
      assert (InvokerBytecodeGenerator
          .isStaticallyInvocable(ArrayAccessor.OBJECT_ARRAY_SETTER.internalMemberName()));
    }

    static int getElementI(int[] a, int i) {
      return a[i];
    }

    static long getElementJ(long[] a, int i) {
      return a[i];
    }

    static float getElementF(float[] a, int i) {
      return a[i];
    }

    static double getElementD(double[] a, int i) {
      return a[i];
    }

    static boolean getElementZ(boolean[] a, int i) {
      return a[i];
    }

    static byte getElementB(byte[] a, int i) {
      return a[i];
    }

    static short getElementS(short[] a, int i) {
      return a[i];
    }

    static char getElementC(char[] a, int i) {
      return a[i];
    }

    static Object getElementL(Object[] a, int i) {
      return a[i];
    }

    static void setElementI(int[] a, int i, int x) {
      a[i] = x;
    }

    static void setElementJ(long[] a, int i, long x) {
      a[i] = x;
    }

    static void setElementF(float[] a, int i, float x) {
      a[i] = x;
    }

    static void setElementD(double[] a, int i, double x) {
      a[i] = x;
    }

    static void setElementZ(boolean[] a, int i, boolean x) {
      a[i] = x;
    }

    static void setElementB(byte[] a, int i, byte x) {
      a[i] = x;
    }

    static void setElementS(short[] a, int i, short x) {
      a[i] = x;
    }

    static void setElementC(char[] a, int i, char x) {
      a[i] = x;
    }

    static void setElementL(Object[] a, int i, Object x) {
      a[i] = x;
    }

    static String name(Class<?> arrayClass, boolean isSetter) {
      Class<?> elemClass = arrayClass.getComponentType();
      if (elemClass == null) {
        throw newIllegalArgumentException("not an array", arrayClass);
      }
      return (!isSetter ? "getElement" : "setElement") + Wrapper.basicTypeChar(elemClass);
    }

    static MethodType type(Class<?> arrayClass, boolean isSetter) {
      Class<?> elemClass = arrayClass.getComponentType();
      Class<?> arrayArgClass = arrayClass;
      if (!elemClass.isPrimitive()) {
        arrayArgClass = Object[].class;
        elemClass = Object.class;
      }
      return !isSetter ?
          MethodType.methodType(elemClass, arrayArgClass, int.class) :
          MethodType.methodType(void.class, arrayArgClass, int.class, elemClass);
    }

    static MethodType correctType(Class<?> arrayClass, boolean isSetter) {
      Class<?> elemClass = arrayClass.getComponentType();
      return !isSetter ?
          MethodType.methodType(elemClass, arrayClass, int.class) :
          MethodType.methodType(void.class, arrayClass, int.class, elemClass);
    }

    static MethodHandle getAccessor(Class<?> arrayClass, boolean isSetter) {
      String name = name(arrayClass, isSetter);
      MethodType type = type(arrayClass, isSetter);
      try {
        return IMPL_LOOKUP.findStatic(ArrayAccessor.class, name, type);
      } catch (ReflectiveOperationException ex) {
        throw uncaughtException(ex);
      }
    }
  }

  /**
   * Create a JVM-level adapter method handle to conform the given method
   * handle to the similar newType, using only pairwise argument conversions.
   * For each argument, convert incoming argument to the exact type needed.
   * The argument conversions allowed are casting, boxing and unboxing,
   * integral widening or narrowing, and floating point widening or narrowing.
   *
   * @param srcType required call type
   * @param target original method handle
   * @param strict if true, only asType conversions are allowed; if false, explicitCastArguments
   * conversions allowed
   * @param monobox if true, unboxing conversions are assumed to be exactly typed (Integer to int
   * only, not long or double)
   * @return an adapter to the original handle with the desired new type, or the original target if
   * the types are already identical or null if the adaptation cannot be made
   */
  static MethodHandle makePairwiseConvert(MethodHandle target, MethodType srcType,
      boolean strict, boolean monobox) {
    MethodType dstType = target.type();
    if (srcType == dstType) {
      return target;
    }
    return makePairwiseConvertByEditor(target, srcType, strict, monobox);
  }

  private static int countNonNull(Object[] array) {
    int count = 0;
    for (Object x : array) {
      if (x != null) {
        ++count;
      }
    }
    return count;
  }

  static MethodHandle makePairwiseConvertByEditor(MethodHandle target, MethodType srcType,
      boolean strict, boolean monobox) {
    Object[] convSpecs = computeValueConversions(srcType, target.type(), strict, monobox);
    int convCount = countNonNull(convSpecs);
    if (convCount == 0) {
      return target.viewAsType(srcType, strict);
    }
    MethodType basicSrcType = srcType.basicType();
    MethodType midType = target.type().basicType();
    BoundMethodHandle mh = target.rebind();
    // FIXME: Reduce number of bindings when there is more than one Class conversion.
    // FIXME: Reduce number of bindings when there are repeated conversions.
    for (int i = 0; i < convSpecs.length - 1; i++) {
      Object convSpec = convSpecs[i];
      if (convSpec == null) {
        continue;
      }
      MethodHandle fn;
      if (convSpec instanceof Class) {
        fn = Lazy.MH_castReference.bindTo(convSpec);
      } else {
        fn = (MethodHandle) convSpec;
      }
      Class<?> newType = basicSrcType.parameterType(i);
      if (--convCount == 0) {
        midType = srcType;
      } else {
        midType = midType.changeParameterType(i, newType);
      }
      LambdaForm form2 = mh.editor().filterArgumentForm(1 + i, BasicType.basicType(newType));
      mh = mh.copyWithExtendL(midType, form2, fn);
      mh = mh.rebind();
    }
    Object convSpec = convSpecs[convSpecs.length - 1];
    if (convSpec != null) {
      MethodHandle fn;
      if (convSpec instanceof Class) {
        if (convSpec == void.class) {
          fn = null;
        } else {
          fn = Lazy.MH_castReference.bindTo(convSpec);
        }
      } else {
        fn = (MethodHandle) convSpec;
      }
      Class<?> newType = basicSrcType.returnType();
      assert (--convCount == 0);
      midType = srcType;
      if (fn != null) {
        mh = mh.rebind();  // rebind if too complex
        LambdaForm form2 = mh.editor().filterReturnForm(BasicType.basicType(newType), false);
        mh = mh.copyWithExtendL(midType, form2, fn);
      } else {
        LambdaForm form2 = mh.editor().filterReturnForm(BasicType.basicType(newType), true);
        mh = mh.copyWith(midType, form2);
      }
    }
    assert (convCount == 0);
    assert (mh.type().equals(srcType));
    return mh;
  }

  static MethodHandle makePairwiseConvertIndirect(MethodHandle target, MethodType srcType,
      boolean strict, boolean monobox) {
    assert (target.type().parameterCount() == srcType.parameterCount());
    // Calculate extra arguments (temporaries) required in the names array.
    Object[] convSpecs = computeValueConversions(srcType, target.type(), strict, monobox);
    final int INARG_COUNT = srcType.parameterCount();
    int convCount = countNonNull(convSpecs);
    boolean retConv = (convSpecs[INARG_COUNT] != null);
    boolean retVoid = srcType.returnType() == void.class;
    if (retConv && retVoid) {
      convCount -= 1;
      retConv = false;
    }

    final int IN_MH = 0;
    final int INARG_BASE = 1;
    final int INARG_LIMIT = INARG_BASE + INARG_COUNT;
    final int NAME_LIMIT = INARG_LIMIT + convCount + 1;
    final int RETURN_CONV = (!retConv ? -1 : NAME_LIMIT - 1);
    final int OUT_CALL = (!retConv ? NAME_LIMIT : RETURN_CONV) - 1;
    final int RESULT = (retVoid ? -1 : NAME_LIMIT - 1);

    // Now build a LambdaForm.
    MethodType lambdaType = srcType.basicType().invokerType();
    Name[] names = arguments(NAME_LIMIT - INARG_LIMIT, lambdaType);

    // Collect the arguments to the outgoing call, maybe with conversions:
    final int OUTARG_BASE = 0;  // target MH is Name.function, name Name.arguments[0]
    Object[] outArgs = new Object[OUTARG_BASE + INARG_COUNT];

    int nameCursor = INARG_LIMIT;
    for (int i = 0; i < INARG_COUNT; i++) {
      Object convSpec = convSpecs[i];
      if (convSpec == null) {
        // do nothing: difference is trivial
        outArgs[OUTARG_BASE + i] = names[INARG_BASE + i];
        continue;
      }

      Name conv;
      if (convSpec instanceof Class) {
        Class<?> convClass = (Class<?>) convSpec;
        conv = new Name(Lazy.MH_castReference, convClass, names[INARG_BASE + i]);
      } else {
        MethodHandle fn = (MethodHandle) convSpec;
        conv = new Name(fn, names[INARG_BASE + i]);
      }
      assert (names[nameCursor] == null);
      names[nameCursor++] = conv;
      assert (outArgs[OUTARG_BASE + i] == null);
      outArgs[OUTARG_BASE + i] = conv;
    }

    // Build argument array for the call.
    assert (nameCursor == OUT_CALL);
    names[OUT_CALL] = new Name(target, outArgs);

    Object convSpec = convSpecs[INARG_COUNT];
    if (!retConv) {
      assert (OUT_CALL == names.length - 1);
    } else {
      Name conv;
      if (convSpec == void.class) {
        conv = new Name(LambdaForm.constantZero(BasicType.basicType(srcType.returnType())));
      } else if (convSpec instanceof Class) {
        Class<?> convClass = (Class<?>) convSpec;
        conv = new Name(Lazy.MH_castReference, convClass, names[OUT_CALL]);
      } else {
        MethodHandle fn = (MethodHandle) convSpec;
        if (fn.type().parameterCount() == 0) {
          conv = new Name(fn);  // don't pass retval to void conversion
        } else {
          conv = new Name(fn, names[OUT_CALL]);
        }
      }
      assert (names[RETURN_CONV] == null);
      names[RETURN_CONV] = conv;
      assert (RETURN_CONV == names.length - 1);
    }

    LambdaForm form = new LambdaForm("convert", lambdaType.parameterCount(), names, RESULT);
    return SimpleMethodHandle.make(srcType, form);
  }

  /**
   * Identity function, with reference cast.
   *
   * @param t an arbitrary reference type
   * @param x an arbitrary reference value
   * @return the same value x
   */
  @ForceInline
  @SuppressWarnings("unchecked")
  static <T, U> T castReference(Class<? extends T> t, U x) {
    // inlined Class.cast because we can't ForceInline it
    if (x != null && !t.isInstance(x)) {
      throw newClassCastException(t, x);
    }
    return (T) x;
  }

  private static ClassCastException newClassCastException(Class<?> t, Object obj) {
    return new ClassCastException("Cannot cast " + obj.getClass().getName() + " to " + t.getName());
  }

  static Object[] computeValueConversions(MethodType srcType, MethodType dstType,
      boolean strict, boolean monobox) {
    final int INARG_COUNT = srcType.parameterCount();
    Object[] convSpecs = new Object[INARG_COUNT + 1];
    for (int i = 0; i <= INARG_COUNT; i++) {
      boolean isRet = (i == INARG_COUNT);
      Class<?> src = isRet ? dstType.returnType() : srcType.parameterType(i);
      Class<?> dst = isRet ? srcType.returnType() : dstType.parameterType(i);
      if (!VerifyType.isNullConversion(src, dst, /*keepInterfaces=*/ strict)) {
        convSpecs[i] = valueConversion(src, dst, strict, monobox);
      }
    }
    return convSpecs;
  }

  static MethodHandle makePairwiseConvert(MethodHandle target, MethodType srcType,
      boolean strict) {
    return makePairwiseConvert(target, srcType, strict, /*monobox=*/ false);
  }

  /**
   * Find a conversion function from the given source to the given destination.
   * This conversion function will be used as a LF NamedFunction.
   * Return a Class object if a simple cast is needed.
   * Return void.class if void is involved.
   */
  static Object valueConversion(Class<?> src, Class<?> dst, boolean strict, boolean monobox) {
    assert (!VerifyType
        .isNullConversion(src, dst, /*keepInterfaces=*/ strict));  // caller responsibility
    if (dst == void.class) {
      return dst;
    }
    MethodHandle fn;
    if (src.isPrimitive()) {
      if (src == void.class) {
        return void.class;  // caller must recognize this specially
      } else if (dst.isPrimitive()) {
        // Examples: int->byte, byte->int, boolean->int (!strict)
        fn = ValueConversions.convertPrimitive(src, dst);
      } else {
        // Examples: int->Integer, boolean->Object, float->Number
        Wrapper wsrc = Wrapper.forPrimitiveType(src);
        fn = ValueConversions.boxExact(wsrc);
        assert (fn.type().parameterType(0) == wsrc.primitiveType());
        assert (fn.type().returnType() == wsrc.wrapperType());
        if (!VerifyType.isNullConversion(wsrc.wrapperType(), dst, strict)) {
          // Corner case, such as int->Long, which will probably fail.
          MethodType mt = MethodType.methodType(dst, src);
          if (strict) {
            fn = fn.asType(mt);
          } else {
            fn = MethodHandleImpl.makePairwiseConvert(fn, mt, /*strict=*/ false);
          }
        }
      }
    } else if (dst.isPrimitive()) {
      Wrapper wdst = Wrapper.forPrimitiveType(dst);
      if (monobox || src == wdst.wrapperType()) {
        // Use a strongly-typed unboxer, if possible.
        fn = ValueConversions.unboxExact(wdst, strict);
      } else {
        // Examples:  Object->int, Number->int, Comparable->int, Byte->int
        // must include additional conversions
        // src must be examined at runtime, to detect Byte, Character, etc.
        fn = (strict
            ? ValueConversions.unboxWiden(wdst)
            : ValueConversions.unboxCast(wdst));
      }
    } else {
      // Simple reference conversion.
      // Note:  Do not check for a class hierarchy relation
      // between src and dst.  In all cases a 'null' argument
      // will pass the cast conversion.
      return dst;
    }
    assert (fn.type().parameterCount() <= 1) :
        "pc" + Arrays.asList(src.getSimpleName(), dst.getSimpleName(), fn);
    return fn;
  }

  static MethodHandle makeVarargsCollector(MethodHandle target, Class<?> arrayType) {
    MethodType type = target.type();
    int last = type.parameterCount() - 1;
    if (type.parameterType(last) != arrayType) {
      target = target.asType(type.changeParameterType(last, arrayType));
    }
    target = target.asFixedArity();  // make sure this attribute is turned off
    return new AsVarargsCollector(target, arrayType);
  }

  private static final class AsVarargsCollector extends DelegatingMethodHandle {

    private final MethodHandle target;
    private final Class<?> arrayType;
    private @Stable
    MethodHandle asCollectorCache;

    AsVarargsCollector(MethodHandle target, Class<?> arrayType) {
      this(target.type(), target, arrayType);
    }

    AsVarargsCollector(MethodType type, MethodHandle target, Class<?> arrayType) {
      super(type, target);
      this.target = target;
      this.arrayType = arrayType;
      this.asCollectorCache = target.asCollector(arrayType, 0);
    }

    @Override
    public boolean isVarargsCollector() {
      return true;
    }

    @Override
    protected MethodHandle getTarget() {
      return target;
    }

    @Override
    public MethodHandle asFixedArity() {
      return target;
    }

    @Override
    MethodHandle setVarargs(MemberName member) {
      if (member.isVarargs()) {
        return this;
      }
      return asFixedArity();
    }

    @Override
    public MethodHandle asTypeUncached(MethodType newType) {
      MethodType type = this.type();
      int collectArg = type.parameterCount() - 1;
      int newArity = newType.parameterCount();
      if (newArity == collectArg + 1 &&
          type.parameterType(collectArg).isAssignableFrom(newType.parameterType(collectArg))) {
        // if arity and trailing parameter are compatible, do normal thing
        return asTypeCache = asFixedArity().asType(newType);
      }
      // check cache
      MethodHandle acc = asCollectorCache;
      if (acc != null && acc.type().parameterCount() == newArity) {
        return asTypeCache = acc.asType(newType);
      }
      // build and cache a collector
      int arrayLength = newArity - collectArg;
      MethodHandle collector;
      try {
        collector = asFixedArity().asCollector(arrayType, arrayLength);
        assert (collector.type().parameterCount() == newArity) :
            "newArity=" + newArity + " but collector=" + collector;
      } catch (IllegalArgumentException ex) {
        throw new WrongMethodTypeException("cannot build collector", ex);
      }
      asCollectorCache = collector;
      return asTypeCache = collector.asType(newType);
    }

    @Override
    boolean viewAsTypeChecks(MethodType newType, boolean strict) {
      super.viewAsTypeChecks(newType, true);
      if (strict) {
        return true;
      }
      // extra assertion for non-strict checks:
      assert (type().lastParameterType().getComponentType()
          .isAssignableFrom(
              newType.lastParameterType().getComponentType()))
          : Arrays.asList(this, newType);
      return true;
    }
  }

  /**
   * Factory method:  Spread selected argument.
   */
  static MethodHandle makeSpreadArguments(MethodHandle target,
      Class<?> spreadArgType, int spreadArgPos, int spreadArgCount) {
    MethodType targetType = target.type();

    for (int i = 0; i < spreadArgCount; i++) {
      Class<?> arg = VerifyType.spreadArgElementType(spreadArgType, i);
      if (arg == null) {
        arg = Object.class;
      }
      targetType = targetType.changeParameterType(spreadArgPos + i, arg);
    }
    target = target.asType(targetType);

    MethodType srcType = targetType
        .replaceParameterTypes(spreadArgPos, spreadArgPos + spreadArgCount, spreadArgType);
    // Now build a LambdaForm.
    MethodType lambdaType = srcType.invokerType();
    Name[] names = arguments(spreadArgCount + 2, lambdaType);
    int nameCursor = lambdaType.parameterCount();
    int[] indexes = new int[targetType.parameterCount()];

    for (int i = 0, argIndex = 1; i < targetType.parameterCount() + 1; i++, argIndex++) {
      Class<?> src = lambdaType.parameterType(i);
      if (i == spreadArgPos) {
        // Spread the array.
        MethodHandle aload = MethodHandles.arrayElementGetter(spreadArgType);
        Name array = names[argIndex];
        names[nameCursor++] = new Name(Lazy.NF_checkSpreadArgument, array, spreadArgCount);
        for (int j = 0; j < spreadArgCount; i++, j++) {
          indexes[i] = nameCursor;
          names[nameCursor++] = new Name(aload, array, j);
        }
      } else if (i < indexes.length) {
        indexes[i] = argIndex;
      }
    }
    assert (nameCursor == names.length - 1);  // leave room for the final call

    // Build argument array for the call.
    Name[] targetArgs = new Name[targetType.parameterCount()];
    for (int i = 0; i < targetType.parameterCount(); i++) {
      int idx = indexes[i];
      targetArgs[i] = names[idx];
    }
    names[names.length - 1] = new Name(target, (Object[]) targetArgs);

    LambdaForm form = new LambdaForm("spread", lambdaType.parameterCount(), names);
    return SimpleMethodHandle.make(srcType, form);
  }

  static void checkSpreadArgument(Object av, int n) {
    if (av == null) {
      if (n == 0) {
        return;
      }
    } else if (av instanceof Object[]) {
      int len = ((Object[]) av).length;
      if (len == n) {
        return;
      }
    } else {
      int len = java.lang.reflect.Array.getLength(av);
      if (len == n) {
        return;
      }
    }
    // fall through to error:
    throw newIllegalArgumentException("array is not of length " + n);
  }

  /**
   * Pre-initialized NamedFunctions for bootstrapping purposes.
   * Factored in an inner class to delay initialization until first usage.
   */
  static class Lazy {

    private static final Class<?> MHI = MethodHandleImpl.class;

    private static final MethodHandle[] ARRAYS;
    private static final MethodHandle[] FILL_ARRAYS;

    static final NamedFunction NF_checkSpreadArgument;
    static final NamedFunction NF_guardWithCatch;
    static final NamedFunction NF_throwException;
    static final NamedFunction NF_profileBoolean;

    static final MethodHandle MH_castReference;
    static final MethodHandle MH_selectAlternative;
    static final MethodHandle MH_copyAsPrimitiveArray;
    static final MethodHandle MH_fillNewTypedArray;
    static final MethodHandle MH_fillNewArray;
    static final MethodHandle MH_arrayIdentity;

    static {
      ARRAYS = makeArrays();
      FILL_ARRAYS = makeFillArrays();

      try {
        NF_checkSpreadArgument = new NamedFunction(
            MHI.getDeclaredMethod("checkSpreadArgument", Object.class, int.class));
        NF_guardWithCatch = new NamedFunction(
            MHI.getDeclaredMethod("guardWithCatch", MethodHandle.class, Class.class,
                MethodHandle.class, Object[].class));
        NF_throwException = new NamedFunction(
            MHI.getDeclaredMethod("throwException", Throwable.class));
        NF_profileBoolean = new NamedFunction(
            MHI.getDeclaredMethod("profileBoolean", boolean.class, int[].class));

        NF_checkSpreadArgument.resolve();
        NF_guardWithCatch.resolve();
        NF_throwException.resolve();
        NF_profileBoolean.resolve();

        MH_castReference = IMPL_LOOKUP.findStatic(MHI, "castReference",
            MethodType.methodType(Object.class, Class.class, Object.class));
        MH_copyAsPrimitiveArray = IMPL_LOOKUP.findStatic(MHI, "copyAsPrimitiveArray",
            MethodType.methodType(Object.class, Wrapper.class, Object[].class));
        MH_arrayIdentity = IMPL_LOOKUP.findStatic(MHI, "identity",
            MethodType.methodType(Object[].class, Object[].class));
        MH_fillNewArray = IMPL_LOOKUP.findStatic(MHI, "fillNewArray",
            MethodType.methodType(Object[].class, Integer.class, Object[].class));
        MH_fillNewTypedArray = IMPL_LOOKUP.findStatic(MHI, "fillNewTypedArray",
            MethodType.methodType(Object[].class, Object[].class, Integer.class, Object[].class));

        MH_selectAlternative = makeIntrinsic(
            IMPL_LOOKUP.findStatic(MHI, "selectAlternative",
                MethodType.methodType(MethodHandle.class, boolean.class, MethodHandle.class,
                    MethodHandle.class)),
            Intrinsic.SELECT_ALTERNATIVE);
      } catch (ReflectiveOperationException ex) {
        throw newInternalError(ex);
      }
    }
  }

  /**
   * Factory method:  Collect or filter selected argument(s).
   */
  static MethodHandle makeCollectArguments(MethodHandle target,
      MethodHandle collector, int collectArgPos, boolean retainOriginalArgs) {
    MethodType targetType = target.type();          // (a..., c, [b...])=>r
    MethodType collectorType = collector.type();    // (b...)=>c
    int collectArgCount = collectorType.parameterCount();
    Class<?> collectValType = collectorType.returnType();
    int collectValCount = (collectValType == void.class ? 0 : 1);
    MethodType srcType = targetType                 // (a..., [b...])=>r
        .dropParameterTypes(collectArgPos, collectArgPos + collectValCount);
    if (!retainOriginalArgs) {                      // (a..., b...)=>r
      srcType = srcType.insertParameterTypes(collectArgPos, collectorType.parameterList());
    }
    // in  arglist: [0: ...keep1 | cpos: collect...  | cpos+cacount: keep2... ]
    // out arglist: [0: ...keep1 | cpos: collectVal? | cpos+cvcount: keep2... ]
    // out(retain): [0: ...keep1 | cpos: cV? coll... | cpos+cvc+cac: keep2... ]

    // Now build a LambdaForm.
    MethodType lambdaType = srcType.invokerType();
    Name[] names = arguments(2, lambdaType);
    final int collectNamePos = names.length - 2;
    final int targetNamePos = names.length - 1;

    Name[] collectorArgs = Arrays
        .copyOfRange(names, 1 + collectArgPos, 1 + collectArgPos + collectArgCount);
    names[collectNamePos] = new Name(collector, (Object[]) collectorArgs);

    // Build argument array for the target.
    // Incoming LF args to copy are: [ (mh) headArgs collectArgs tailArgs ].
    // Output argument array is [ headArgs (collectVal)? (collectArgs)? tailArgs ].
    Name[] targetArgs = new Name[targetType.parameterCount()];
    int inputArgPos = 1;  // incoming LF args to copy to target
    int targetArgPos = 0;  // fill pointer for targetArgs
    int chunk = collectArgPos;  // |headArgs|
    System.arraycopy(names, inputArgPos, targetArgs, targetArgPos, chunk);
    inputArgPos += chunk;
    targetArgPos += chunk;
    if (collectValType != void.class) {
      targetArgs[targetArgPos++] = names[collectNamePos];
    }
    chunk = collectArgCount;
    if (retainOriginalArgs) {
      System.arraycopy(names, inputArgPos, targetArgs, targetArgPos, chunk);
      targetArgPos += chunk;   // optionally pass on the collected chunk
    }
    inputArgPos += chunk;
    chunk = targetArgs.length - targetArgPos;  // all the rest
    System.arraycopy(names, inputArgPos, targetArgs, targetArgPos, chunk);
    assert (inputArgPos + chunk == collectNamePos);  // use of rest of input args also
    names[targetNamePos] = new Name(target, (Object[]) targetArgs);

    LambdaForm form = new LambdaForm("collect", lambdaType.parameterCount(), names);
    return SimpleMethodHandle.make(srcType, form);
  }

  @LambdaForm.Hidden
  static MethodHandle selectAlternative(boolean testResult, MethodHandle target,
      MethodHandle fallback) {
    if (testResult) {
      return target;
    } else {
      return fallback;
    }
  }

  // Intrinsified by C2. Counters are used during parsing to calculate branch frequencies.
  @LambdaForm.Hidden
  static boolean profileBoolean(boolean result, int[] counters) {
    // Profile is int[2] where [0] and [1] correspond to false and true occurrences respectively.
    int idx = result ? 1 : 0;
    try {
      counters[idx] = Math.addExact(counters[idx], 1);
    } catch (ArithmeticException e) {
      // Avoid continuous overflow by halving the problematic count.
      counters[idx] = counters[idx] / 2;
    }
    return result;
  }

  static MethodHandle makeGuardWithTest(MethodHandle test,
      MethodHandle target,
      MethodHandle fallback) {
    MethodType type = target.type();
    assert (test.type().equals(type.changeReturnType(boolean.class)) && fallback.type()
        .equals(type));
    MethodType basicType = type.basicType();
    LambdaForm form = makeGuardWithTestForm(basicType);
    BoundMethodHandle mh;
    try {
      if (PROFILE_GWT) {
        int[] counts = new int[2];
        mh = (BoundMethodHandle)
            BoundMethodHandle.speciesData_LLLL().constructor().invokeBasic(type, form,
                (Object) test, (Object) profile(target), (Object) profile(fallback), counts);
      } else {
        mh = (BoundMethodHandle)
            BoundMethodHandle.speciesData_LLL().constructor().invokeBasic(type, form,
                (Object) test, (Object) profile(target), (Object) profile(fallback));
      }
    } catch (Throwable ex) {
      throw uncaughtException(ex);
    }
    assert (mh.type() == type);
    return mh;
  }


  static MethodHandle profile(MethodHandle target) {
    if (DONT_INLINE_THRESHOLD >= 0) {
      return makeBlockInlningWrapper(target);
    } else {
      return target;
    }
  }

  /**
   * Block inlining during JIT-compilation of a target method handle if it hasn't been invoked
   * enough times. Corresponding LambdaForm has @DontInline when compiled into bytecode.
   */
  static MethodHandle makeBlockInlningWrapper(MethodHandle target) {
    LambdaForm lform = PRODUCE_BLOCK_INLINING_FORM.apply(target);
    return new CountingWrapper(target, lform,
        PRODUCE_BLOCK_INLINING_FORM, PRODUCE_REINVOKER_FORM,
        DONT_INLINE_THRESHOLD);
  }

  /**
   * Constructs reinvoker lambda form which block inlining during JIT-compilation for a particular
   * method handle
   */
  private static final Function<MethodHandle, LambdaForm> PRODUCE_BLOCK_INLINING_FORM = new Function<MethodHandle, LambdaForm>() {
    @Override
    public LambdaForm apply(MethodHandle target) {
      return DelegatingMethodHandle.makeReinvokerForm(target,
          MethodTypeForm.LF_DELEGATE_BLOCK_INLINING, CountingWrapper.class, "reinvoker.dontInline",
          false,
          DelegatingMethodHandle.NF_getTarget, CountingWrapper.NF_maybeStopCounting);
    }
  };

  /**
   * Constructs simple reinvoker lambda form for a particular method handle
   */
  private static final Function<MethodHandle, LambdaForm> PRODUCE_REINVOKER_FORM = new Function<MethodHandle, LambdaForm>() {
    @Override
    public LambdaForm apply(MethodHandle target) {
      return DelegatingMethodHandle.makeReinvokerForm(target,
          MethodTypeForm.LF_DELEGATE, DelegatingMethodHandle.class,
          DelegatingMethodHandle.NF_getTarget);
    }
  };

  /**
   * Counting method handle. It has 2 states: counting and non-counting.
   * It is in counting state for the first n invocations and then transitions to non-counting state.
   * Behavior in counting and non-counting states is determined by lambda forms produced by
   * countingFormProducer & nonCountingFormProducer respectively.
   */
  static class CountingWrapper extends DelegatingMethodHandle {

    private final MethodHandle target;
    private int count;
    private Function<MethodHandle, LambdaForm> countingFormProducer;
    private Function<MethodHandle, LambdaForm> nonCountingFormProducer;
    private volatile boolean isCounting;

    private CountingWrapper(MethodHandle target, LambdaForm lform,
        Function<MethodHandle, LambdaForm> countingFromProducer,
        Function<MethodHandle, LambdaForm> nonCountingFormProducer,
        int count) {
      super(target.type(), lform);
      this.target = target;
      this.count = count;
      this.countingFormProducer = countingFromProducer;
      this.nonCountingFormProducer = nonCountingFormProducer;
      this.isCounting = (count > 0);
    }

    @Hidden
    @Override
    protected MethodHandle getTarget() {
      return target;
    }

    @Override
    public MethodHandle asTypeUncached(MethodType newType) {
      MethodHandle newTarget = target.asType(newType);
      MethodHandle wrapper;
      if (isCounting) {
        LambdaForm lform;
        lform = countingFormProducer.apply(newTarget);
        wrapper = new CountingWrapper(newTarget, lform, countingFormProducer,
            nonCountingFormProducer, DONT_INLINE_THRESHOLD);
      } else {
        wrapper = newTarget; // no need for a counting wrapper anymore
      }
      return (asTypeCache = wrapper);
    }

    boolean countDown() {
      if (count <= 0) {
        // Try to limit number of updates. MethodHandle.updateForm() doesn't guarantee LF update visibility.
        if (isCounting) {
          isCounting = false;
          return true;
        } else {
          return false;
        }
      } else {
        --count;
        return false;
      }
    }

    @Hidden
    static void maybeStopCounting(Object o1) {
      CountingWrapper wrapper = (CountingWrapper) o1;
      if (wrapper.countDown()) {
        // Reached invocation threshold. Replace counting behavior with a non-counting one.
        LambdaForm lform = wrapper.nonCountingFormProducer.apply(wrapper.target);
        lform
            .compileToBytecode(); // speed up warmup by avoiding LF interpretation again after transition
        wrapper.updateForm(lform);
      }
    }

    static final NamedFunction NF_maybeStopCounting;

    static {
      Class<?> THIS_CLASS = CountingWrapper.class;
      try {
        NF_maybeStopCounting = new NamedFunction(
            THIS_CLASS.getDeclaredMethod("maybeStopCounting", Object.class));
      } catch (ReflectiveOperationException ex) {
        throw newInternalError(ex);
      }
    }
  }

  static LambdaForm makeGuardWithTestForm(MethodType basicType) {
    LambdaForm lform = basicType.form().cachedLambdaForm(MethodTypeForm.LF_GWT);
    if (lform != null) {
      return lform;
    }
    final int THIS_MH = 0;  // the BMH_LLL
    final int ARG_BASE = 1;  // start of incoming arguments
    final int ARG_LIMIT = ARG_BASE + basicType.parameterCount();
    int nameCursor = ARG_LIMIT;
    final int GET_TEST = nameCursor++;
    final int GET_TARGET = nameCursor++;
    final int GET_FALLBACK = nameCursor++;
    final int GET_COUNTERS = PROFILE_GWT ? nameCursor++ : -1;
    final int CALL_TEST = nameCursor++;
    final int PROFILE = (GET_COUNTERS != -1) ? nameCursor++ : -1;
    final int TEST = nameCursor - 1; // previous statement: either PROFILE or CALL_TEST
    final int SELECT_ALT = nameCursor++;
    final int CALL_TARGET = nameCursor++;
    assert (CALL_TARGET == SELECT_ALT + 1);  // must be true to trigger IBG.emitSelectAlternative

    MethodType lambdaType = basicType.invokerType();
    Name[] names = arguments(nameCursor - ARG_LIMIT, lambdaType);

    BoundMethodHandle.SpeciesData data =
        (GET_COUNTERS != -1) ? BoundMethodHandle.speciesData_LLLL()
            : BoundMethodHandle.speciesData_LLL();
    names[THIS_MH] = names[THIS_MH].withConstraint(data);
    names[GET_TEST] = new Name(data.getterFunction(0), names[THIS_MH]);
    names[GET_TARGET] = new Name(data.getterFunction(1), names[THIS_MH]);
    names[GET_FALLBACK] = new Name(data.getterFunction(2), names[THIS_MH]);
    if (GET_COUNTERS != -1) {
      names[GET_COUNTERS] = new Name(data.getterFunction(3), names[THIS_MH]);
    }
    Object[] invokeArgs = Arrays.copyOfRange(names, 0, ARG_LIMIT, Object[].class);

    // call test
    MethodType testType = basicType.changeReturnType(boolean.class).basicType();
    invokeArgs[0] = names[GET_TEST];
    names[CALL_TEST] = new Name(testType, invokeArgs);

    // profile branch
    if (PROFILE != -1) {
      names[PROFILE] = new Name(Lazy.NF_profileBoolean, names[CALL_TEST], names[GET_COUNTERS]);
    }
    // call selectAlternative
    names[SELECT_ALT] = new Name(Lazy.MH_selectAlternative, names[TEST], names[GET_TARGET],
        names[GET_FALLBACK]);

    // call target or fallback
    invokeArgs[0] = names[SELECT_ALT];
    names[CALL_TARGET] = new Name(basicType, invokeArgs);

    lform = new LambdaForm("guard", lambdaType.parameterCount(), names, /*forceInline=*/true);

    return basicType.form().setCachedLambdaForm(MethodTypeForm.LF_GWT, lform);
  }

  /**
   * The LambaForm shape for catchException combinator is the following:
   * <blockquote><pre>{@code
   *  guardWithCatch=Lambda(a0:L,a1:L,a2:L)=>{
   *    t3:L=BoundMethodHandle$Species_LLLLL.argL0(a0:L);
   *    t4:L=BoundMethodHandle$Species_LLLLL.argL1(a0:L);
   *    t5:L=BoundMethodHandle$Species_LLLLL.argL2(a0:L);
   *    t6:L=BoundMethodHandle$Species_LLLLL.argL3(a0:L);
   *    t7:L=BoundMethodHandle$Species_LLLLL.argL4(a0:L);
   *    t8:L=MethodHandle.invokeBasic(t6:L,a1:L,a2:L);
   *    t9:L=MethodHandleImpl.guardWithCatch(t3:L,t4:L,t5:L,t8:L);
   *   t10:I=MethodHandle.invokeBasic(t7:L,t9:L);t10:I}
   * }</pre></blockquote>
   *
   * argL0 and argL2 are target and catcher method handles. argL1 is exception class. argL3 and
   * argL4 are auxiliary method handles: argL3 boxes arguments and wraps them into Object[]
   * (ValueConversions.array()) and argL4 unboxes result if necessary (ValueConversions.unbox()).
   *
   * Having t8 and t10 passed outside and not hardcoded into a lambda form allows to share lambda
   * forms among catchException combinators with the same basic type.
   */
  private static LambdaForm makeGuardWithCatchForm(MethodType basicType) {
    MethodType lambdaType = basicType.invokerType();

    LambdaForm lform = basicType.form().cachedLambdaForm(MethodTypeForm.LF_GWC);
    if (lform != null) {
      return lform;
    }
    final int THIS_MH = 0;  // the BMH_LLLLL
    final int ARG_BASE = 1;  // start of incoming arguments
    final int ARG_LIMIT = ARG_BASE + basicType.parameterCount();

    int nameCursor = ARG_LIMIT;
    final int GET_TARGET = nameCursor++;
    final int GET_CLASS = nameCursor++;
    final int GET_CATCHER = nameCursor++;
    final int GET_COLLECT_ARGS = nameCursor++;
    final int GET_UNBOX_RESULT = nameCursor++;
    final int BOXED_ARGS = nameCursor++;
    final int TRY_CATCH = nameCursor++;
    final int UNBOX_RESULT = nameCursor++;

    Name[] names = arguments(nameCursor - ARG_LIMIT, lambdaType);

    BoundMethodHandle.SpeciesData data = BoundMethodHandle.speciesData_LLLLL();
    names[THIS_MH] = names[THIS_MH].withConstraint(data);
    names[GET_TARGET] = new Name(data.getterFunction(0), names[THIS_MH]);
    names[GET_CLASS] = new Name(data.getterFunction(1), names[THIS_MH]);
    names[GET_CATCHER] = new Name(data.getterFunction(2), names[THIS_MH]);
    names[GET_COLLECT_ARGS] = new Name(data.getterFunction(3), names[THIS_MH]);
    names[GET_UNBOX_RESULT] = new Name(data.getterFunction(4), names[THIS_MH]);

    // FIXME: rework argument boxing/result unboxing logic for LF interpretation

    // t_{i}:L=MethodHandle.invokeBasic(collectArgs:L,a1:L,...);
    MethodType collectArgsType = basicType.changeReturnType(Object.class);
    MethodHandle invokeBasic = MethodHandles.basicInvoker(collectArgsType);
    Object[] args = new Object[invokeBasic.type().parameterCount()];
    args[0] = names[GET_COLLECT_ARGS];
    System.arraycopy(names, ARG_BASE, args, 1, ARG_LIMIT - ARG_BASE);
    names[BOXED_ARGS] = new Name(makeIntrinsic(invokeBasic, Intrinsic.GUARD_WITH_CATCH), args);

    // t_{i+1}:L=MethodHandleImpl.guardWithCatch(target:L,exType:L,catcher:L,t_{i}:L);
    Object[] gwcArgs = new Object[]{names[GET_TARGET], names[GET_CLASS], names[GET_CATCHER],
        names[BOXED_ARGS]};
    names[TRY_CATCH] = new Name(Lazy.NF_guardWithCatch, gwcArgs);

    // t_{i+2}:I=MethodHandle.invokeBasic(unbox:L,t_{i+1}:L);
    MethodHandle invokeBasicUnbox = MethodHandles
        .basicInvoker(MethodType.methodType(basicType.rtype(), Object.class));
    Object[] unboxArgs = new Object[]{names[GET_UNBOX_RESULT], names[TRY_CATCH]};
    names[UNBOX_RESULT] = new Name(invokeBasicUnbox, unboxArgs);

    lform = new LambdaForm("guardWithCatch", lambdaType.parameterCount(), names);

    return basicType.form().setCachedLambdaForm(MethodTypeForm.LF_GWC, lform);
  }

  static MethodHandle makeGuardWithCatch(MethodHandle target,
      Class<? extends Throwable> exType,
      MethodHandle catcher) {
    MethodType type = target.type();
    LambdaForm form = makeGuardWithCatchForm(type.basicType());

    // Prepare auxiliary method handles used during LambdaForm interpreation.
    // Box arguments and wrap them into Object[]: ValueConversions.array().
    MethodType varargsType = type.changeReturnType(Object[].class);
    MethodHandle collectArgs = varargsArray(type.parameterCount()).asType(varargsType);
    // Result unboxing: ValueConversions.unbox() OR ValueConversions.identity() OR ValueConversions.ignore().
    MethodHandle unboxResult;
    Class<?> rtype = type.returnType();
    if (rtype.isPrimitive()) {
      if (rtype == void.class) {
        unboxResult = ValueConversions.ignore();
      } else {
        Wrapper w = Wrapper.forPrimitiveType(type.returnType());
        unboxResult = ValueConversions.unboxExact(w);
      }
    } else {
      unboxResult = MethodHandles.identity(Object.class);
    }

    BoundMethodHandle.SpeciesData data = BoundMethodHandle.speciesData_LLLLL();
    BoundMethodHandle mh;
    try {
      mh = (BoundMethodHandle)
          data.constructor()
              .invokeBasic(type, form, (Object) target, (Object) exType, (Object) catcher,
                  (Object) collectArgs, (Object) unboxResult);
    } catch (Throwable ex) {
      throw uncaughtException(ex);
    }
    assert (mh.type() == type);
    return mh;
  }

  /**
   * Intrinsified during LambdaForm compilation
   * (see {@link InvokerBytecodeGenerator#emitGuardWithCatch emitGuardWithCatch}).
   */
  @LambdaForm.Hidden
  static Object guardWithCatch(MethodHandle target, Class<? extends Throwable> exType,
      MethodHandle catcher,
      Object... av) throws Throwable {
    // Use asFixedArity() to avoid unnecessary boxing of last argument for VarargsCollector case.
    try {
      return target.asFixedArity().invokeWithArguments(av);
    } catch (Throwable t) {
      if (!exType.isInstance(t)) {
        throw t;
      }
      return catcher.asFixedArity().invokeWithArguments(prepend(t, av));
    }
  }

  /**
   * Prepend an element {@code elem} to an {@code array}.
   */
  @LambdaForm.Hidden
  private static Object[] prepend(Object elem, Object[] array) {
    Object[] newArray = new Object[array.length + 1];
    newArray[0] = elem;
    System.arraycopy(array, 0, newArray, 1, array.length);
    return newArray;
  }

  static MethodHandle throwException(MethodType type) {
    assert (Throwable.class.isAssignableFrom(type.parameterType(0)));
    int arity = type.parameterCount();
    if (arity > 1) {
      MethodHandle mh = throwException(type.dropParameterTypes(1, arity));
      mh = MethodHandles.dropArguments(mh, 1, type.parameterList().subList(1, arity));
      return mh;
    }
    return makePairwiseConvert(Lazy.NF_throwException.resolvedHandle(), type, false, true);
  }

  static <T extends Throwable> Empty throwException(T t) throws T {
    throw t;
  }

  static MethodHandle[] FAKE_METHOD_HANDLE_INVOKE = new MethodHandle[2];

  static MethodHandle fakeMethodHandleInvoke(MemberName method) {
    int idx;
    assert (method.isMethodHandleInvoke());
    switch (method.getName()) {
      case "invoke":
        idx = 0;
        break;
      case "invokeExact":
        idx = 1;
        break;
      default:
        throw new InternalError(method.getName());
    }
    MethodHandle mh = FAKE_METHOD_HANDLE_INVOKE[idx];
    if (mh != null) {
      return mh;
    }
    MethodType type = MethodType.methodType(Object.class, UnsupportedOperationException.class,
        MethodHandle.class, Object[].class);
    mh = throwException(type);
    mh = mh.bindTo(new UnsupportedOperationException("cannot reflectively invoke MethodHandle"));
    if (!method.getInvocationType().equals(mh.type())) {
      throw new InternalError(method.toString());
    }
    mh = mh.withInternalMemberName(method, false);
    mh = mh.asVarargsCollector(Object[].class);
    assert (method.isVarargs());
    FAKE_METHOD_HANDLE_INVOKE[idx] = mh;
    return mh;
  }

  /**
   * Create an alias for the method handle which, when called,
   * appears to be called from the same class loader and protection domain
   * as hostClass.
   * This is an expensive no-op unless the method which is called
   * is sensitive to its caller.  A small number of system methods
   * are in this category, including Class.forName and Method.invoke.
   */
  static MethodHandle bindCaller(MethodHandle mh, Class<?> hostClass) {
    return BindCaller.bindCaller(mh, hostClass);
  }

  // Put the whole mess into its own nested class.
  // That way we can lazily load the code and set up the constants.
  private static class BindCaller {

    static MethodHandle bindCaller(MethodHandle mh, Class<?> hostClass) {
      // Do not use this function to inject calls into system classes.
      if (hostClass == null
          || (hostClass.isArray() ||
          hostClass.isPrimitive() ||
          hostClass.getName().startsWith("java.") ||
          hostClass.getName().startsWith("sun."))) {
        throw new InternalError();  // does not happen, and should not anyway
      }
      // For simplicity, convert mh to a varargs-like method.
      MethodHandle vamh = prepareForInvoker(mh);
      // Cache the result of makeInjectedInvoker once per argument class.
      MethodHandle bccInvoker = CV_makeInjectedInvoker.get(hostClass);
      return restoreToType(bccInvoker.bindTo(vamh), mh, hostClass);
    }

    private static MethodHandle makeInjectedInvoker(Class<?> hostClass) {
      Class<?> bcc = UNSAFE.defineAnonymousClass(hostClass, T_BYTES, null);
      if (hostClass.getClassLoader() != bcc.getClassLoader()) {
        throw new InternalError(hostClass.getName() + " (CL)");
      }
      try {
        if (hostClass.getProtectionDomain() != bcc.getProtectionDomain()) {
          throw new InternalError(hostClass.getName() + " (PD)");
        }
      } catch (SecurityException ex) {
        // Self-check was blocked by security manager.  This is OK.
        // In fact the whole try body could be turned into an assertion.
      }
      try {
        MethodHandle init = IMPL_LOOKUP.findStatic(bcc, "init", MethodType.methodType(void.class));
        init.invokeExact();  // force initialization of the class
      } catch (Throwable ex) {
        throw uncaughtException(ex);
      }
      MethodHandle bccInvoker;
      try {
        MethodType invokerMT = MethodType
            .methodType(Object.class, MethodHandle.class, Object[].class);
        bccInvoker = IMPL_LOOKUP.findStatic(bcc, "invoke_V", invokerMT);
      } catch (ReflectiveOperationException ex) {
        throw uncaughtException(ex);
      }
      // Test the invoker, to ensure that it really injects into the right place.
      try {
        MethodHandle vamh = prepareForInvoker(MH_checkCallerClass);
        Object ok = bccInvoker.invokeExact(vamh, new Object[]{hostClass, bcc});
      } catch (Throwable ex) {
        throw new InternalError(ex);
      }
      return bccInvoker;
    }

    private static ClassValue<MethodHandle> CV_makeInjectedInvoker = new ClassValue<MethodHandle>() {
      @Override
      protected MethodHandle computeValue(Class<?> hostClass) {
        return makeInjectedInvoker(hostClass);
      }
    };

    // Adapt mh so that it can be called directly from an injected invoker:
    private static MethodHandle prepareForInvoker(MethodHandle mh) {
      mh = mh.asFixedArity();
      MethodType mt = mh.type();
      int arity = mt.parameterCount();
      MethodHandle vamh = mh.asType(mt.generic());
      vamh.internalForm().compileToBytecode();  // eliminate LFI stack frames
      vamh = vamh.asSpreader(Object[].class, arity);
      vamh.internalForm().compileToBytecode();  // eliminate LFI stack frames
      return vamh;
    }

    // Undo the adapter effect of prepareForInvoker:
    private static MethodHandle restoreToType(MethodHandle vamh,
        MethodHandle original,
        Class<?> hostClass) {
      MethodType type = original.type();
      MethodHandle mh = vamh.asCollector(Object[].class, type.parameterCount());
      MemberName member = original.internalMemberName();
      mh = mh.asType(type);
      mh = new WrappedMember(mh, type, member, original.isInvokeSpecial(), hostClass);
      return mh;
    }

    private static final MethodHandle MH_checkCallerClass;

    static {
      final Class<?> THIS_CLASS = BindCaller.class;
      assert (checkCallerClass(THIS_CLASS, THIS_CLASS));
      try {
        MH_checkCallerClass = IMPL_LOOKUP
            .findStatic(THIS_CLASS, "checkCallerClass",
                MethodType.methodType(boolean.class, Class.class, Class.class));
        assert ((boolean) MH_checkCallerClass.invokeExact(THIS_CLASS, THIS_CLASS));
      } catch (Throwable ex) {
        throw new InternalError(ex);
      }
    }

    @CallerSensitive
    private static boolean checkCallerClass(Class<?> expected, Class<?> expected2) {
      // This method is called via MH_checkCallerClass and so it's
      // correct to ask for the immediate caller here.
      Class<?> actual = Reflection.getCallerClass();
      if (actual != expected && actual != expected2) {
        throw new InternalError("found " + actual.getName() + ", expected " + expected.getName()
            + (expected == expected2 ? "" : ", or else " + expected2.getName()));
      }
      return true;
    }

    private static final byte[] T_BYTES;

    static {
      final Object[] values = {null};
      AccessController.doPrivileged(new PrivilegedAction<Void>() {
        public Void run() {
          try {
            Class<T> tClass = T.class;
            String tName = tClass.getName();
            String tResource = tName.substring(tName.lastIndexOf('.') + 1) + ".class";
            java.net.URLConnection uconn = tClass.getResource(tResource).openConnection();
            int len = uconn.getContentLength();
            byte[] bytes = new byte[len];
            try (java.io.InputStream str = uconn.getInputStream()) {
              int nr = str.read(bytes);
              if (nr != len) {
                throw new java.io.IOException(tResource);
              }
            }
            values[0] = bytes;
          } catch (java.io.IOException ex) {
            throw new InternalError(ex);
          }
          return null;
        }
      });
      T_BYTES = (byte[]) values[0];
    }

    // The following class is used as a template for Unsafe.defineAnonymousClass:
    private static class T {

      static void init() {
      }  // side effect: initializes this class

      static Object invoke_V(MethodHandle vamh, Object[] args) throws Throwable {
        return vamh.invokeExact(args);
      }
    }
  }


  /**
   * This subclass allows a wrapped method handle to be re-associated with an arbitrary member name.
   */
  private static final class WrappedMember extends DelegatingMethodHandle {

    private final MethodHandle target;
    private final MemberName member;
    private final Class<?> callerClass;
    private final boolean isInvokeSpecial;

    private WrappedMember(MethodHandle target, MethodType type,
        MemberName member, boolean isInvokeSpecial,
        Class<?> callerClass) {
      super(type, target);
      this.target = target;
      this.member = member;
      this.callerClass = callerClass;
      this.isInvokeSpecial = isInvokeSpecial;
    }

    @Override
    MemberName internalMemberName() {
      return member;
    }

    @Override
    Class<?> internalCallerClass() {
      return callerClass;
    }

    @Override
    boolean isInvokeSpecial() {
      return isInvokeSpecial;
    }

    @Override
    protected MethodHandle getTarget() {
      return target;
    }

    @Override
    public MethodHandle asTypeUncached(MethodType newType) {
      // This MH is an alias for target, except for the MemberName
      // Drop the MemberName if there is any conversion.
      return asTypeCache = target.asType(newType);
    }
  }

  static MethodHandle makeWrappedMember(MethodHandle target, MemberName member,
      boolean isInvokeSpecial) {
    if (member.equals(target.internalMemberName()) && isInvokeSpecial == target.isInvokeSpecial()) {
      return target;
    }
    return new WrappedMember(target, target.type(), member, isInvokeSpecial, null);
  }

  /**
   * Intrinsic IDs
   */
    /*non-public*/
  enum Intrinsic {
    SELECT_ALTERNATIVE,
    GUARD_WITH_CATCH,
    NEW_ARRAY,
    ARRAY_LOAD,
    ARRAY_STORE,
    IDENTITY,
    ZERO,
    NONE // no intrinsic associated
  }

  /**
   * Mark arbitrary method handle as intrinsic.
   * InvokerBytecodeGenerator uses this info to produce more efficient bytecode shape.
   */
  private static final class IntrinsicMethodHandle extends DelegatingMethodHandle {

    private final MethodHandle target;
    private final Intrinsic intrinsicName;

    IntrinsicMethodHandle(MethodHandle target, Intrinsic intrinsicName) {
      super(target.type(), target);
      this.target = target;
      this.intrinsicName = intrinsicName;
    }

    @Override
    protected MethodHandle getTarget() {
      return target;
    }

    @Override
    Intrinsic intrinsicName() {
      return intrinsicName;
    }

    @Override
    public MethodHandle asTypeUncached(MethodType newType) {
      // This MH is an alias for target, except for the intrinsic name
      // Drop the name if there is any conversion.
      return asTypeCache = target.asType(newType);
    }

    @Override
    String internalProperties() {
      return super.internalProperties() +
          "\n& Intrinsic=" + intrinsicName;
    }

    @Override
    public MethodHandle asCollector(Class<?> arrayType, int arrayLength) {
      if (intrinsicName == Intrinsic.IDENTITY) {
        MethodType resultType = type().asCollectorType(arrayType, arrayLength);
        MethodHandle newArray = MethodHandleImpl.varargsArray(arrayType, arrayLength);
        return newArray.asType(resultType);
      }
      return super.asCollector(arrayType, arrayLength);
    }
  }

  static MethodHandle makeIntrinsic(MethodHandle target, Intrinsic intrinsicName) {
    if (intrinsicName == target.intrinsicName()) {
      return target;
    }
    return new IntrinsicMethodHandle(target, intrinsicName);
  }

  static MethodHandle makeIntrinsic(MethodType type, LambdaForm form, Intrinsic intrinsicName) {
    return new IntrinsicMethodHandle(SimpleMethodHandle.make(type, form), intrinsicName);
  }

  /// Collection of multiple arguments.

  private static MethodHandle findCollector(String name, int nargs, Class<?> rtype,
      Class<?>... ptypes) {
    MethodType type = MethodType.genericMethodType(nargs)
        .changeReturnType(rtype)
        .insertParameterTypes(0, ptypes);
    try {
      return IMPL_LOOKUP.findStatic(MethodHandleImpl.class, name, type);
    } catch (ReflectiveOperationException ex) {
      return null;
    }
  }

  private static final Object[] NO_ARGS_ARRAY = {};

  private static Object[] makeArray(Object... args) {
    return args;
  }

  private static Object[] array() {
    return NO_ARGS_ARRAY;
  }

  private static Object[] array(Object a0) {
    return makeArray(a0);
  }

  private static Object[] array(Object a0, Object a1) {
    return makeArray(a0, a1);
  }

  private static Object[] array(Object a0, Object a1, Object a2) {
    return makeArray(a0, a1, a2);
  }

  private static Object[] array(Object a0, Object a1, Object a2, Object a3) {
    return makeArray(a0, a1, a2, a3);
  }

  private static Object[] array(Object a0, Object a1, Object a2, Object a3,
      Object a4) {
    return makeArray(a0, a1, a2, a3, a4);
  }

  private static Object[] array(Object a0, Object a1, Object a2, Object a3,
      Object a4, Object a5) {
    return makeArray(a0, a1, a2, a3, a4, a5);
  }

  private static Object[] array(Object a0, Object a1, Object a2, Object a3,
      Object a4, Object a5, Object a6) {
    return makeArray(a0, a1, a2, a3, a4, a5, a6);
  }

  private static Object[] array(Object a0, Object a1, Object a2, Object a3,
      Object a4, Object a5, Object a6, Object a7) {
    return makeArray(a0, a1, a2, a3, a4, a5, a6, a7);
  }

  private static Object[] array(Object a0, Object a1, Object a2, Object a3,
      Object a4, Object a5, Object a6, Object a7,
      Object a8) {
    return makeArray(a0, a1, a2, a3, a4, a5, a6, a7, a8);
  }

  private static Object[] array(Object a0, Object a1, Object a2, Object a3,
      Object a4, Object a5, Object a6, Object a7,
      Object a8, Object a9) {
    return makeArray(a0, a1, a2, a3, a4, a5, a6, a7, a8, a9);
  }

  private static MethodHandle[] makeArrays() {
    ArrayList<MethodHandle> mhs = new ArrayList<>();
    for (; ; ) {
      MethodHandle mh = findCollector("array", mhs.size(), Object[].class);
      if (mh == null) {
        break;
      }
      mh = makeIntrinsic(mh, Intrinsic.NEW_ARRAY);
      mhs.add(mh);
    }
    assert (mhs.size() == 11);  // current number of methods
    return mhs.toArray(new MethodHandle[MAX_ARITY + 1]);
  }

  // filling versions of the above:
  // using Integer len instead of int len and no varargs to avoid bootstrapping problems
  private static Object[] fillNewArray(Integer len, Object[] /*not ...*/ args) {
    Object[] a = new Object[len];
    fillWithArguments(a, 0, args);
    return a;
  }

  private static Object[] fillNewTypedArray(Object[] example, Integer len,
      Object[] /*not ...*/ args) {
    Object[] a = Arrays.copyOf(example, len);
    assert (a.getClass() != Object[].class);
    fillWithArguments(a, 0, args);
    return a;
  }

  private static void fillWithArguments(Object[] a, int pos, Object... args) {
    System.arraycopy(args, 0, a, pos, args.length);
  }

  // using Integer pos instead of int pos to avoid bootstrapping problems
  private static Object[] fillArray(Integer pos, Object[] a, Object a0) {
    fillWithArguments(a, pos, a0);
    return a;
  }

  private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1) {
    fillWithArguments(a, pos, a0, a1);
    return a;
  }

  private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1, Object a2) {
    fillWithArguments(a, pos, a0, a1, a2);
    return a;
  }

  private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1, Object a2,
      Object a3) {
    fillWithArguments(a, pos, a0, a1, a2, a3);
    return a;
  }

  private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1, Object a2,
      Object a3,
      Object a4) {
    fillWithArguments(a, pos, a0, a1, a2, a3, a4);
    return a;
  }

  private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1, Object a2,
      Object a3,
      Object a4, Object a5) {
    fillWithArguments(a, pos, a0, a1, a2, a3, a4, a5);
    return a;
  }

  private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1, Object a2,
      Object a3,
      Object a4, Object a5, Object a6) {
    fillWithArguments(a, pos, a0, a1, a2, a3, a4, a5, a6);
    return a;
  }

  private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1, Object a2,
      Object a3,
      Object a4, Object a5, Object a6, Object a7) {
    fillWithArguments(a, pos, a0, a1, a2, a3, a4, a5, a6, a7);
    return a;
  }

  private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1, Object a2,
      Object a3,
      Object a4, Object a5, Object a6, Object a7,
      Object a8) {
    fillWithArguments(a, pos, a0, a1, a2, a3, a4, a5, a6, a7, a8);
    return a;
  }

  private static Object[] fillArray(Integer pos, Object[] a, Object a0, Object a1, Object a2,
      Object a3,
      Object a4, Object a5, Object a6, Object a7,
      Object a8, Object a9) {
    fillWithArguments(a, pos, a0, a1, a2, a3, a4, a5, a6, a7, a8, a9);
    return a;
  }

  private static final int FILL_ARRAYS_COUNT = 11; // current number of fillArray methods

  private static MethodHandle[] makeFillArrays() {
    ArrayList<MethodHandle> mhs = new ArrayList<>();
    mhs.add(null);  // there is no empty fill; at least a0 is required
    for (; ; ) {
      MethodHandle mh = findCollector("fillArray", mhs.size(), Object[].class, Integer.class,
          Object[].class);
      if (mh == null) {
        break;
      }
      mhs.add(mh);
    }
    assert (mhs.size() == FILL_ARRAYS_COUNT);
    return mhs.toArray(new MethodHandle[0]);
  }

  private static Object copyAsPrimitiveArray(Wrapper w, Object... boxes) {
    Object a = w.makeArray(boxes.length);
    w.copyArrayUnboxing(boxes, 0, a, 0, boxes.length);
    return a;
  }

  /**
   * Return a method handle that takes the indicated number of Object
   * arguments and returns an Object array of them, as if for varargs.
   */
  static MethodHandle varargsArray(int nargs) {
    MethodHandle mh = Lazy.ARRAYS[nargs];
    if (mh != null) {
      return mh;
    }
    mh = findCollector("array", nargs, Object[].class);
    if (mh != null) {
      mh = makeIntrinsic(mh, Intrinsic.NEW_ARRAY);
    }
    if (mh != null) {
      return Lazy.ARRAYS[nargs] = mh;
    }
    mh = buildVarargsArray(Lazy.MH_fillNewArray, Lazy.MH_arrayIdentity, nargs);
    assert (assertCorrectArity(mh, nargs));
    mh = makeIntrinsic(mh, Intrinsic.NEW_ARRAY);
    return Lazy.ARRAYS[nargs] = mh;
  }

  private static boolean assertCorrectArity(MethodHandle mh, int arity) {
    assert (mh.type().parameterCount() == arity) : "arity != " + arity + ": " + mh;
    return true;
  }

  // Array identity function (used as Lazy.MH_arrayIdentity).
  static <T> T[] identity(T[] x) {
    return x;
  }

  private static MethodHandle buildVarargsArray(MethodHandle newArray, MethodHandle finisher,
      int nargs) {
    // Build up the result mh as a sequence of fills like this:
    //   finisher(fill(fill(newArrayWA(23,x1..x10),10,x11..x20),20,x21..x23))
    // The various fill(_,10*I,___*[J]) are reusable.
    int leftLen = Math.min(nargs, LEFT_ARGS);  // absorb some arguments immediately
    int rightLen = nargs - leftLen;
    MethodHandle leftCollector = newArray.bindTo(nargs);
    leftCollector = leftCollector.asCollector(Object[].class, leftLen);
    MethodHandle mh = finisher;
    if (rightLen > 0) {
      MethodHandle rightFiller = fillToRight(LEFT_ARGS + rightLen);
      if (mh == Lazy.MH_arrayIdentity) {
        mh = rightFiller;
      } else {
        mh = MethodHandles.collectArguments(mh, 0, rightFiller);
      }
    }
    if (mh == Lazy.MH_arrayIdentity) {
      mh = leftCollector;
    } else {
      mh = MethodHandles.collectArguments(mh, 0, leftCollector);
    }
    return mh;
  }

  private static final int LEFT_ARGS = FILL_ARRAYS_COUNT - 1;
  private static final MethodHandle[] FILL_ARRAY_TO_RIGHT = new MethodHandle[MAX_ARITY + 1];

  /**
   * fill_array_to_right(N).invoke(a, argL..arg[N-1])
   * fills a[L]..a[N-1] with corresponding arguments,
   * and then returns a.  The value L is a global constant (LEFT_ARGS).
   */
  private static MethodHandle fillToRight(int nargs) {
    MethodHandle filler = FILL_ARRAY_TO_RIGHT[nargs];
    if (filler != null) {
      return filler;
    }
    filler = buildFiller(nargs);
    assert (assertCorrectArity(filler, nargs - LEFT_ARGS + 1));
    return FILL_ARRAY_TO_RIGHT[nargs] = filler;
  }

  private static MethodHandle buildFiller(int nargs) {
    if (nargs <= LEFT_ARGS) {
      return Lazy.MH_arrayIdentity;  // no args to fill; return the array unchanged
    }
    // we need room for both mh and a in mh.invoke(a, arg*[nargs])
    final int CHUNK = LEFT_ARGS;
    int rightLen = nargs % CHUNK;
    int midLen = nargs - rightLen;
    if (rightLen == 0) {
      midLen = nargs - (rightLen = CHUNK);
      if (FILL_ARRAY_TO_RIGHT[midLen] == null) {
        // build some precursors from left to right
        for (int j = LEFT_ARGS % CHUNK; j < midLen; j += CHUNK) {
          if (j > LEFT_ARGS) {
            fillToRight(j);
          }
        }
      }
    }
    if (midLen < LEFT_ARGS) {
      rightLen = nargs - (midLen = LEFT_ARGS);
    }
    assert (rightLen > 0);
    MethodHandle midFill = fillToRight(midLen);  // recursive fill
    MethodHandle rightFill = Lazy.FILL_ARRAYS[rightLen].bindTo(midLen);  // [midLen..nargs-1]
    assert (midFill.type().parameterCount() == 1 + midLen - LEFT_ARGS);
    assert (rightFill.type().parameterCount() == 1 + rightLen);

    // Combine the two fills:
    //   right(mid(a, x10..x19), x20..x23)
    // The final product will look like this:
    //   right(mid(newArrayLeft(24, x0..x9), x10..x19), x20..x23)
    if (midLen == LEFT_ARGS) {
      return rightFill;
    } else {
      return MethodHandles.collectArguments(rightFill, 0, midFill);
    }
  }

  // Type-polymorphic version of varargs maker.
  private static final ClassValue<MethodHandle[]> TYPED_COLLECTORS
      = new ClassValue<MethodHandle[]>() {
    @Override
    protected MethodHandle[] computeValue(Class<?> type) {
      return new MethodHandle[256];
    }
  };

  static final int MAX_JVM_ARITY = 255;  // limit imposed by the JVM

  /**
   * Return a method handle that takes the indicated number of
   * typed arguments and returns an array of them.
   * The type argument is the array type.
   */
  static MethodHandle varargsArray(Class<?> arrayType, int nargs) {
    Class<?> elemType = arrayType.getComponentType();
    if (elemType == null) {
      throw new IllegalArgumentException("not an array: " + arrayType);
    }
    // FIXME: Need more special casing and caching here.
    if (nargs >= MAX_JVM_ARITY / 2 - 1) {
      int slots = nargs;
      final int MAX_ARRAY_SLOTS = MAX_JVM_ARITY - 1;  // 1 for receiver MH
      if (slots <= MAX_ARRAY_SLOTS && elemType.isPrimitive()) {
        slots *= Wrapper.forPrimitiveType(elemType).stackSlots();
      }
      if (slots > MAX_ARRAY_SLOTS) {
        throw new IllegalArgumentException(
            "too many arguments: " + arrayType.getSimpleName() + ", length " + nargs);
      }
    }
    if (elemType == Object.class) {
      return varargsArray(nargs);
    }
    // other cases:  primitive arrays, subtypes of Object[]
    MethodHandle cache[] = TYPED_COLLECTORS.get(elemType);
    MethodHandle mh = nargs < cache.length ? cache[nargs] : null;
    if (mh != null) {
      return mh;
    }
    if (nargs == 0) {
      Object example = java.lang.reflect.Array.newInstance(arrayType.getComponentType(), 0);
      mh = MethodHandles.constant(arrayType, example);
    } else if (elemType.isPrimitive()) {
      MethodHandle builder = Lazy.MH_fillNewArray;
      MethodHandle producer = buildArrayProducer(arrayType);
      mh = buildVarargsArray(builder, producer, nargs);
    } else {
      Class<? extends Object[]> objArrayType = arrayType.asSubclass(Object[].class);
      Object[] example = Arrays.copyOf(NO_ARGS_ARRAY, 0, objArrayType);
      MethodHandle builder = Lazy.MH_fillNewTypedArray.bindTo(example);
      MethodHandle producer = Lazy.MH_arrayIdentity; // must be weakly typed
      mh = buildVarargsArray(builder, producer, nargs);
    }
    mh = mh
        .asType(MethodType.methodType(arrayType, Collections.<Class<?>>nCopies(nargs, elemType)));
    mh = makeIntrinsic(mh, Intrinsic.NEW_ARRAY);
    assert (assertCorrectArity(mh, nargs));
    if (nargs < cache.length) {
      cache[nargs] = mh;
    }
    return mh;
  }

  private static MethodHandle buildArrayProducer(Class<?> arrayType) {
    Class<?> elemType = arrayType.getComponentType();
    assert (elemType.isPrimitive());
    return Lazy.MH_copyAsPrimitiveArray.bindTo(Wrapper.forPrimitiveType(elemType));
  }

  /*non-public*/
  static void assertSame(Object mh1, Object mh2) {
    if (mh1 != mh2) {
      String msg = String.format("mh1 != mh2: mh1 = %s (form: %s); mh2 = %s (form: %s)",
          mh1, ((MethodHandle) mh1).form,
          mh2, ((MethodHandle) mh2).form);
      throw newInternalError(msg);
    }
  }
}
